Fluoro-chloro-butanes



Patented Apr. 9, 1946 STATES PATENT OFFEC FLUORO-CHLORO -BUTANES NoDrawing. Application July 8, 1942,

Serial No. 450,185

3 Claims.

This invention relates to halogenated hydrocarbons and more particularlyit relates to compounds of the formula CHaCXF--CHC1-CH3, wherein X isfluorine or chlorine.

Ever since the discovery of chloroprene and the discovery thatpolymerized chloroprene is a rubber-like material, considerable interesthas been shown in the possibility of making rubberlike materials bypolymerizing fiuoroprene (2- fiuoro- 1,3 -butadiene), (see U. S. PatentNo. 2,012,223) Many proposed processes for the making of this fluorocompound have been suggested and tried without the discovery of asatisfactory method for its preparation.

I It is an object of this invention to prepare an intermediate for themaking of fluoroprene. Another object is to discover a fluorinatedorganic compound having four carbon atoms which would be a suitableintermediate for the making of fiuoroprene. Another object is to preparefluorochloro-butanes. Other objects will appear hereinafter. 1

These objects have been accomplished by the preparation of2-fluoro-2,3-dichloro-butane and 2,2-difiuoro-3-chloro-butane. Thesecompounds can be prepared by treatment of 2,2,3-trichlorobutane, whichis a known compound, with suitable fluorinating agents; such, forexample, as

antimony trifiuorlde or hydrogen fluoride in the presence of mercuricoxide.

In order that the invention may be more fully understood the followingexamples are given by way of illustration, parts being given by weight.

Example I Eighty-five parts of SbFs was added to seventyseven parts of2,2,3-trichloro-butane and the mixture heated in an oil bath underreflux. The mixture was shaken frequently during reaction. The mixturestarted to reflux at 142 C. and the boiling point gradually dropped, andafter three hours the product was refluxing at 108 C., vaportemperature. The product was distilled out. washed twice with 6NHC1,then with water and dried over N82504. The product was then fractionallydistilled. The principal product obtained was 2 fluoro 2,3 dichlorobutane. A small amount of 2,2-difluoro-S-chloro-butane was alsoobtained.

Example 11 One hundred eighty-five parts of 2,2,8-trichloro-butane wasplaced in a stainless steel pot with four hundred forty-two parts mo andheated to 100 C. during the addition or fifty parts of anhydrous HF.This process required five hours. The reaction products were distilledout under vacuum and the products trapped in Example III Six hundred andforty-four parts of 2,2,3-trichloro-butane was placed in a nickel potwith 447 parts of HgO and heated to C. parts of anhydrous HF wereintroduced with stirring over a period of about three hours, keeping thetemperature at 50-70 C. The reaction products were steam-distilled,washed with 10% NaHSO: solution, followed by 5% NazCO; and water, andfractionally distilled; About 17 parts of 2,2- dlfiuoro-S-chloro-butane,133 parts of 2-fiuoro- 2,3-dichloro-butane and 285 parts of unchanged2,2,3-trichloro-butane were recovered.

2-fiuoro-2,3-dichloro-butane is a liquid having a boiling point of106-109 C. at atmospheric pressure with a specific gravity at 25 C. of1.197 and a refractive index 12. 1.417. The 2,2-dlfiuoro-3-chloro-butaneis a colorless liquid with a boiling point of 72-73 C. at atmosphericpiessure with a specific gravity at 25 C. of 1.128 and a refractiveindex 11 1.363. I

The new compound, 2-fiuoro-2,3-dichloro-bu tane, is a valuableintermediate for the preparation of fiuoroprene by the removal of twomoles of H01. Both new compounds are intermediates used to produce morehighly fiuorinated derivatives of butane.

It will be readily apparent to those skilled in the art that theinvention is not limited to the specific process limitations set forthin the examples but that suitable changes may be made in temperature,pressure, and other reaction conditions without departing from theinvention.

Iclaim:

1. A compound of the formula wherein X is a member of the groupconsisting of chlorine and fluorine.

2. 2-fiuoro-2,3-dichloro-butane. 3. 2,2-difluoro-3- chloro-butane.

FRANK' WILLARD JOHNSON.

